Knowledge of essential amino acid requirement in (preterm) infants is important since excessive or deficient intake might lead to long term morbidity such as obesity (Singhal et al. (2002) Am J Clin Nutr 75:993-9) or suboptimal growth and impaired neurodevelopment outcome (Stephens et al (2009) Pediatrics 2009;123:1337-43).    The branched-chain amino acids (BCAA) leucine (Leu), isoleucine (Ile) and valine (Val) account for 35-40% of the dietary indispensable amino acids in body protein and 14% of the total amino acids in skeletal muscle. Infant nutrition has been formulated using mother's milk, breast milk, as the most ideal composition. However, due to the different amino acid composition of protein sources used for production of infant nutrition, protein levels are most often higher compared to those in breast milk to ensure sufficient intake of BCAA.
It now becomes increasingly clear that early nutrition that is consumed by the infant has metabolic effects on the infant, also later in life, i.e. metabolic imprinting. For example WO 2008/054200 discloses that metabolic imprinting is an important mechanism in programming future health and food is specifically designed to prevent obesity later in life by giving low protein diets. Hence, diets too high or too low in protein may therefore be harmful to the infants. However, the exact requirement of essential amino acids for term and preterm infants is not known.